Air flow over the back of the wheel is generally sufficient to keep the vehicle brakes cooled to a proper functioning level. However, when the vehicle is going very slow or when the vehicle brakes are hot and the vehicle is suddenly stopped, the temperature of the brake will be increased, requiring more air flow through the wheel.
Holes in the trim of the wheel are provided to allow more air flow through the wheel during these conditions, but these holes reduce the smooth air flow over the external face of the wheel as the vehicle speed increases.
If a solid wheel trim is used, i.e. with no holes, the consumption of fuel is lower than the consumption with a wheel trim provided with holes under the same conditions. However, this solution causes higher brake temperatures for the conditions stated above.
There are known wheels trims provided with holes and comprising one or more elements that, when the speed of the car is high enough, close the holes and permit a smooth air flow over the external face of the wheel, reducing the consumption of fuel.
In these prior art trims, this or each element is associated with a spring, so that the centrifugal force of the wheel, when the vehicle reaches a preset high speed, the or each element against the pressure exerted by the spring to close the holes, and when the speed is lower than said preset speed, the or each element returns to its original position, leaving the holes opened.
However, these known trims do not take into account the temperature of the brakes, just the speed of the vehicle, and they can prevent a suitable cooling of the brakes.
Therefore, the objective of the invention is to provide a wheel trim that permits a lower consumption of fuel when the vehicle runs at a high speed and, at the same time, permits to guarantee a suitable cooling of the brakes, and said wheel trim being simple while keeping the cost as low as possible.